The present invention relates to a process for the hydroconversion of heavy crude oil, an improved regenerable catalyst for use therein and a process for making same.
Petroleum and other hydrocarbonaceous oil fractions are very complex mixtures comprising, in addition to hydrocarbons, various compounds, mainly containing sulfur, nitrogen, oxygen and metals. These compounds are present in variable amounts and nature, depending on the origin of the crude oil and the oil fractions. They usually constitute impurities detrimental to the quality of the oil products for reasons of pollution, corrosion, odor and stability. As a result, considerable effort has been made to develop processes which remove the unwanted compounds. Among the many processes which have been developed, catalytic treatments in the presence of hydrogen are the most common.
The purpose behind most of these treatments is to produce products of good quality from crude oils and residues having a high content of impurities. The treatments aim to improve the yield of liquid products at desirable API gravities while minimizing the amount of coke produced. The treaments also aim to convert as much asphaltene and Conradson carbon as possible and to remove as much sulfur, nitrogen, and metals as possible.
U.S. Pat. No. 1,876,270 to Zorn illustrates a process for the conversion of hydrocarbons of higher boiling point into those of lower boiling point. The process employs complex organometallic compounds which are soluble in the hydrocarbons to be converted as catalysts. Particularly suitable compounds include 1, 3 diketones such as acetylacetones, or homologues thereof such as propenyl and butyryl acetone, or vanadylacetylacetone and the like.
In U.S. Pat. No. 4,066,530 to Aldridge et al., a process for hydroconverting heavy hydrocarbon oil is described in which an iron component is added as solid particles to an oil chargestock along with an oil soluble metal compound which is converted to a catalytically active metal component within the chargestock in the presence of a hydrogen-containing gas. The metal in oil soluble metal compound is selected from the group of Group VB, Group VIB, Group VIIB, and Group VIII metals other than iron, and mixtures thereof. The catalyst may if desired be recovered after the first cycle and reused in subsequent cycles. If necessary, additional elemental material may be added to make up a supplemental batch of catalyst. U.S. Pat. No. 4,134,825 to Beardon, Jr. et al., assigned to the same assignee as the Aldridge et al. patent, illustrates the same process without the iron component addition.
U.S. Pat. No. 4,285,804 to Jacquin et al. illustrates a process wherein a recycled catalyst is used to hydrotreat heavy hydrocarbons in the presence of a non-supported catalyst. In this process, the catalyst in the form of a suspension recovered by fractionation of the reaction product is recycled for use. In a similar hydrogenation process shown in U.S. Pat. No. 4,557,821 to Lopez et al., a non-supported catalyst comprising dispersed particles of a highly active form of molybdenum disulfide is formed. An aqueous catalyst precursor is used to form the final catalyst. The precursor is dispersed into feed oil together with hydrogen sulfide and hydrogen. The mixture is passed to a series of heating zones where the final catalyst is formed. The final non-supported catalyst is characterized by a surface area of about 20 m.sup.2 /g, a pore volume of about 0.05 cc/g, an average pore diameter of about 100 .ANG. and an average particle diameter of about 6 microns. Used catalyst in a slurry form is recycled through any or all of the heating zones.
Still other processes for forming a solid catalyst in a hydroconversion zone are shown in U.S. Pat. Nos. 4,579,646 to Grosboll et al., 4,604,190 to Bearden, Jr. et al. 4,604,189 to Derbyshire et al. and, 4,659,454 to Varghese et al.
U.S. Pat. No. 4,376,037 to Dahlberg et al. illustrates a process for hydrogenating a heavy hydrocarbonaceous oil feed. The process may be a one or two stage process in which the oil is contacted with hydrogen in the presence of an added dispersed hydrogenation catalyst, suspended in the oil, and porous solid contact particles. The catalytic material to be dispersed may be added either as a finely divided transition metal compound such as a transition metal sulfide, nitrate or acetate. Alternatively, it may be added as an aqueous solution of one or more water soluble transition metal compounds such as molybdates, tungstates or vanadates of ammonium or alkali metals or as an oil soluble compounds, e.g. organometallic compounds such as molybdenum napthenates, cobalt napthenates and molybdenum oleates. The porous contact particles are totally or substantially free of catalytic transition metals or transition metal compounds added to impart catalytic activity to the solids. The porous contact particles are preferably inexpensive materials such as alumina, porous silica gel, clays and waste catalyst fines.
One of the deficiencies associated with prior art catalyst systems is the inability to regenerate or reuse the catalysts. Often, it is difficult to recover a used catalyst from the products of the hydroconversion reaction. Multiple processing steps requiring expensive equipment are needed. The cost associated with recovering the catalysts often is greater than the cost associated with producing them elementally. Sometimes, the reused catalyst which is recovered must be discarded because it lacks an acceptable level of activity.
Accordingly, it is an object of the present invention to provide an improved catalyst and process for the hydroconversion of heavy crude oil.
It is a further object of the present invention to provide a catalyst which is regenerable and readily recoverable for use in the above process.
These and other objects and advantages will become more readily apparent from the following description and drawings in which like reference numerals depict like elements.